Ignore the base map detail in this image. I need a way to colour the shapes according to one set of data which is the current standard Nevron map behaviour, but also somehow display a second set of data attached to those same shapes. The example here is using 3D, but Nevron maps can't do that. Is there a mechanism in maps which allows me to associate two sets of data with a set of shapes and have them both visible and understandable?

No there is no build in solution in the diagram which can display this kind of chart. You can theoretically achieve this result if you get the shape coordinates, transform them trough a perspective matrix and then use the transformed shape for the actual diagram. Drawing the bars with a 3D effect is also not a big problem so this can be achieved too, but there is no build in API to achieve that.